It is known that various compositions comprising a polyorganosiloxane as a main component are cured on a surface of a base material such as paper, a synthetic film or a fibrous substrate to form a coating thereon, thereby imparting release properties to a base material against an adhesive substance. Those conventional polyorganosiloxane compositions include compositions which form a coating having a low releasability, and compositions which form a coating having a medium or high releasability. Examples of the former include compositions which are cured by a condensation reaction, as disclosed in, for examples, JP-A-Nos. 47-34447 and 48-22703 (The term "JP-A" as used herein means an "unexamined published Japanese patent application"), and compositions which are cured by an addition reaction as disclosed in, for example, JP-B-No. 52-40918 (The term "JP-B" as used herein means an "examined Japanese patent publication"). Examples of the latter include compositions which contain a copolymer comprising (CH.sub.3).sub.3 SiO.sub.1/2 and SiO.sub.2 units and a silica fine powder as disclosed in, for example, JP-A-No. 52-86985, compositions which are prepared by using vinyl group-containing polysiloxanes having Si02 units as disclosed in, for example, JP-A-Nos. 52-24933 and 55-110155, and compositions which are obtained by equilibrating linear vinyl group-containing polysiloxanes and copolymers comprising (CH.sub.3)3SiO.sub.1/2, (CH.sub.3).sub.2 SiO, (CH.sub.2)SiO.sub.1.5 and SiO.sub.2 units as disclosed in, for example, JP-A-No. 56-53150.
Compositions which can form a coating which reduces a peel force at a high speed peeling are also known. Examples of such compositions include compositions obtained by blending polyorganosiloxanes containing methylvinylsiloxane units and having hydroxyl or vinyl groups at the ends of the molecular chain as disclosed in, for example, JP-A-No. 50-25644, and compositions obtained by adding polyorganosiloxanes containing aryl groups to an addition reaction-type composition as disclosed in, for example, JP-A-No. 60-133051. The coatings formed from those compositions, however, have the problems that a peel force becomes large at a low speed peeling, or a subsequent adhesion rate is decreased.